It is known that, oftentimes, trailers are used in conjunction with vehicles such as motor vehicles. Typically, the trailer is attached to a rear of the motor vehicle. An example of such a trailer has a wheeled body having two tow bars at its forward end, which are secured to a hitch at the rear end of the motor vehicle. However, variation in mass of the trailer requires adjustment of yaw, heave, and roll damping to achieve best trailer stability.
It is also known about means to enhance the stability of a trailer and a vehicle. Typically, either a single fixed damper is placed between the vehicle and the trailer hitch or bi-state shock absorbers are placed on the vehicle rear suspension or a rear steering system of the vehicle is used to stabilize the vehicle and the trailer. Passive yaw dampers have fixed damping characteristics. However, the passive dampers for the trailer hitch do not provide optimum damping for both ride and handling under all conditions and can only be a compromise between ride and handling characteristics of the vehicle. The use of a single degree of freedom linked to the vehicle to control multiple elements does not result in good overall control and the best possible stability for the trailer. The use of vehicle rear suspension damping with bi-state control will also result in a compromised ride and handling of the vehicle and does not influence the yaw and roll dynamics of the trailer significantly. In addition, the rear steering system requires very expensive actuators and extremely complex control.
As a result, it is desirable to provide a trailer stability control apparatus that provides fast control of damping forces. It is also desirable to provide a trailer stability control apparatus that provides control of damping forces over a wide operating range. It is further desirable to provide a trailer stability control apparatus that provides control of damping forces at a relatively low cost. Therefore, there is a need in the art to provide a trailer stability control apparatus that meets these desires.